An autograft in which surgeons remove the medulla portion of one adrenal gland and transplant it into the brain’s caudate nucleus. The procedure is also called adrenal-to-brain transplant. Adrenal medullary transplant is an effort to sidestep the blood-brain barrier by “planting” adrenal medulla cells in the caudate in the hope that they will continue to function and produce the components that the brain can convert to dopamine. The premise for this approach came about in the 1980s, when researchers were able to remove adrenal medullary cells from the body and cultivate them in the laboratory, leading to speculation that the cells could also grow in other parts of the body.
The paired adrenal glands cap the top of each kidney in the central abdomen. Transplanting adrenal medullary tissue to the caudate requires two simultaneous surgeries with separate surgical teams, one to remove one adrenal medulla and the other to implant the adrenal medullary tissue in the caudate. only one adrenal medulla is removed. Because the surgery is lengthy, complex, and involves multiple body systems, complications are common and often serious, sometimes fatal. At present, the American Academy of Neurology classifies adrenal medullary transplant as “unacceptable” as a treatment option because it entails these complications, because there is little objective evidence that the procedure produces long-term benefits, and because other surgical treatments produce results that are at least as effective without such high risk.
Only about 60 adrenal medullary transplants have been performed in the united states and Canada since the 1980s, with mixed results. Among people who recovered from the surgery without major complications, Parkinson’s symptoms such as tremors, bradykinesia, and dyskinesia seemed to improve. All remained on medication therapy, although some were able to reduce the amount of Levodopa they were taking. It does not appear that the transplanted adrenal medulla cells survive very long after transplant; one study that followed patients who died within two years of surgery found at autopsy that there were no remaining adrenal medulla cells in the caudate. Other surgical interventions such as pallidotomy, thalamotomy, deep brain stimulation (DBS), retinal pigmented epithelial cell transplant, and stem cell implant produce similar results with significantly less risk.
